In computer science, a cache is a collection of data that duplicates values stored elsewhere, where the original data is expensive to fetch or recompute, compared to the cost of reading the cache. A web browser is a software application that allows a user to view or download resources that are available on a network, such as on a website on the World Wide Web. Browsers are used to retrieve, access and view resources. Resources include both information resources, e.g., passive content such as text, images, and ‘active’ resources, e.g., scripts such as JAVASCRIPT. Browsers run on personal computers and mobile devices. Commonly used browsers presently include, for example, GOOGLE CHROME available from Google Inc., FIREFOX available from Mozilla, INTERNET EXPLORER available from Microsoft Corp., SAFARI available from Apple. Inc. and OPERA from Opera Software, ASA.
Web browsers use caches to improve the performance of the access and viewing functions. Interaction with web resources is most effective when it is responsive, e.g., happens without ‘lag’ or delay between request and display. In some cases, a user interface of a browser may become unresponsive due to improper rendering of content for display. A browser's user interface may also become unresponsive if it is waiting for content to be rendered for display. Browser caches may be used to reduce the lag of resource presentation and otherwise improve the performance of a web browser.
Because caches are finite in size, in order for new resources to be stored in the cache, other resources must be ‘evicted’ or removed from the cache. Different strategies for deciding which data to store in, and evict from caches are used.